This invention relates to a printing apparatus and a printing control method, and more particularly, to a printhead for performing printing in accordance with an ink-jet method, and an ink-jet printing apparatus and a printing control method using the printhead.
In a conventional long printing-width ink-jet printhead, a heater board having about 64, 128 or 256 printing elements is integrated in one chip (hereinbelow, referred to as a xe2x80x9cheater board (HB)xe2x80x9d), and a plurality of HBs are arrayed and attached onto a base plate with high precision. The printhead has ink channels and ink discharge orifices (hereinbelow, referred to as xe2x80x9cdischarge orificesxe2x80x9d) corresponding to the printing elements of the respective HBs.
The printhead is controlled by using printing element designation signals, common to all the HBs, for designating the printing elements of the HBs, and heat control signals prepared in HB units. The recent long printing-width printhead (hereinafter referred to as a xe2x80x9cline type headxe2x80x9d) has 20 or more HBs mounted on its base plate. As the number of control signals from a print control circuit to the line type head increases, heat control signals for the respective HBs in the line type head are generated with block designation signals for dividing the HBs into several blocks and driving the HBs in block units and HB heat signals common to all the blocks, so that increment in the number of control signals outputted to the line type head is suppressed.
FIG. 8 is a block diagram showing the construction of a driving circuit which drives a printhead having 24 HBs by dividing the 24 HBs into 6 blocks by 4 blocks.
In FIG. 8, reference numeral 1 denotes a print control circuit which generates various print control signals; 2, a decoder which converts binary code data designating blocks into signals corresponding to the respective blocks; 3, a 2-input AND gate which outputs an effective heat signal to an HB when a block designation signal and a heat signal corresponding to the HB in the block are both effective; 4 to 9, blocks each including 4 HBs; 10, HBs; and 13, a line type head.
Note that a block denoted by numeral 4 is a first block; a block denoted by numeral 5, a second block; a block denoted by numeral 6, a third block; a block denoted by numeral 7, a fourth block; a block denoted by numeral 8, a fifth block; and a block denoted by numeral 9, a sixth block.
Further, numeral 101 denotes binary code block designation signals BLOCK (0-2), designating a block to be driven; 102, block heat signals BHEET (1-6) for the respective blocks; 103, HB heat signals IHEET (1-4) for the respective HBs 10 in the respective blocks; and 104, heat enable signals HE (1-24) for the respective HBs 10.
FIG. 9 is a timing chart showing the respective signals used in the driving circuit as shown in FIG. 8.
In FIG. 9, all the block designation signals BLOCK (0-2) are turned to xe2x80x9cLOWxe2x80x9d to designate the first block, and the HB heat signals IHEET (1-4) are sequentially turned to xe2x80x9cHIGHxe2x80x9d for the four HBs 10 in the first block, to drive the four HBs 10 in the first block. Next, the block designation signals BLOCK (0-2) are turned to xe2x80x9cHIGHxe2x80x9d, xe2x80x9cLOWxe2x80x9d, and xe2x80x9cLOWxe2x80x9d respectively, to designate the second block, and the HB heat signals IHEET (1-4) are sequentially turned to xe2x80x9cHIGHxe2x80x9d to drive the four HBs 10 in the second block.
The HBs 10 in the third to sixth blocks are driven in a similar manner. Thus, print control is performed on the 24 HBs 10 by the print control circuit by using only 7 signal lines, for the block designation signals BLOCK (0-2) 101 and the HB heat signals IHEET (1-4) 103.
In case of the above-described conventional line type head, if drive to one HB has been completed and then the next HB is driven, the printing time is long and the speed of printing is lowered, however, if a plurality of HBs are simultaneously driven, as the maximum electric consumption during the drive increases, a power source having a large current capacity is required. Accordingly, as shown in the timing chart of FIG. 9, within a block, the respective HBs are driven while heating start timing is shifted little by little within a range avoiding much increment in electric consumption, so that the printing time is shortened.
For this purpose, in the above-described conventional art, within a block, as the HB heat signals IHEET (1-4) are provided for the respective HBs, the above print control to shift the heating start timing can be easily realized. However, when print operation moves from one block to the other block, the HB drive cannot be started before completion of the HB drive in the previous block. Thus the continuity in the drive is broken.
Further, in recent line type heads, as several tens of HBs are mounted, the number of blocks in print control is large in correspondence with the considerably large number of HBs, and the number of occurrence of discontinuity in drive between blocks is larger. As a result, the printing speed in the entire printhead is further lowered.
Accordingly, it is an object of the present invention to provide a printing apparatus and a printing control method which improve continuity in time-division block drive in a printhead and realize high speed printing.
According to one aspect of the present invention, the foregoing object is attained by providing a printing apparatus that performs printing on a print medium by dividing a plurality of printing elements included in a printhead into a plurality of blocks and time-divisionally driving the respective blocks, comprising: first selection-signal generation output means for generating a first selection signal to select an odd-numbered block from the plurality of blocks and outputting the first selection signal to the printhead; second selection-signal generation output means for generating a second selection signal to select an even-numbered block from the plurality of blocks and outputting the second selection signal to the printhead; first drive-signal generation output means for generating a first drive signal to drive printing elements included in the odd-numbered block and outputting the first drive signal to the printhead; second drive-signal generation output means for outputting a second drive signal to drive printing elements included in the even-numbered block and outputting the second drive signal to the printhead; and control means for output-controlling the first and second selection signals such that drive to the odd-numbered block and drive to the even-numbered block are started alternately, and controlling the first and second selection-signal generation output means and the first and second drive-signal generation output means such that an output of the second drive signal to drive the printing elements included in the even-numbered block is started prior to completion of an output of the first drive signal to drive the printing elements included in the odd-numbered block.
According to another aspect of the present invention, the foregoing object is attained by providing a printing apparatus that performs printing on a print medium by dividing a plurality of printing elements included in a printhead into a plurality of blocks and time-divisionally driving the respective blocks, comprising: selection-control signal generation output means for generating a selection control signal to select an odd-numbered block and an even-numbered block from the plurality of blocks and outputting the selection control signal to the printhead; first drive-signal generation output means for generating a first drive signal to drive printing elements included in the odd-numbered block and outputting the first drive signal to the printhead; second drive-signal generation output means for generating a second drive signal to drive printing elements included in the even-numbered block and outputting the second drive signal to the printhead; and control means for output-controlling the selection control signal such that drive to the odd-numbered block and drive to the even-numbered block are started alternately, and controlling the first and second selection-signal generation output means and the first and second drive-signal generation output means such that an output of the second drive signal to drive the printing elements included in the even-numbered block is started prior to completion of an output of the first drive signal to drive the printing elements included in the odd-numbered block.
In the above construction, it is preferable that the printhead includes: a first selection-signal generation circuit that generates a first selection signal to select the odd-numbered block based on the selection control signal; and a second selection-signal generation circuit that generates a second selection signal to select the even-numbered block based on the selection control signal.
In any of these constructions, the number of the printing elements included in the odd-numbered block and the even-numbered block is two or more, and the first drive signal and the second drive signal respectively comprise a plurality of signal pulses so as to respectively drive the plurality of printing elements. The plurality of signal pulses are sequentially outputted at predetermined time intervals.
Note that it is preferable that the printhead is an ink-jet printhead that performs printing by discharging ink. In this case, it is more preferable that the ink-jet printhead has electrothermal transducers to generate thermal energy to be supplied to the ink, so as to discharge the ink by utilizing the thermal energy.
According to still another aspect of the present invention, the foregoing object is attained by providing a printing control method for performing printing on a print medium by dividing a plurality of printing elements included in a printhead into a plurality of blocks and time-divisionally driving the respective blocks, comprising: a first selection-signal generation output step of generating a first selection signal to select an odd-numbered block from the plurality of blocks and outputting the first selection signal to the printhead; a second selection-signal generation output step of generating a second selection signal to select an even-numbered block from the plurality of blocks and outputting the second selection signal to the printhead; a first control step of output-controlling the first and second selection signals such that drive to the odd-numbered block and drive to the even-numbered block are started alternately; a first drive-signal generation output step of generating a first drive signal to drive printing elements included in the odd-numbered block and outputting the first drive signal to the printhead; a second drive-signal generation output step of generating a second drive signal to drive printing elements included in the even-numbered block and outputting the second drive signal to the printhead; and a second control step of output-controlling the first and second drive signals such that an output of the second drive signal to drive the printing elements included in the even-numbered block is started prior to completion of an output of the first drive signal to drive the printing elements included in the odd-numbered block.
In accordance with the present invention as described above, among the plurality of blocks of the printhead, the first selection signal to select an odd-numbered block is generated and outputted to the printhead, and among the plurality of blocks, the second selection signal to select an even-numbered block is generated and outputted to the printhead. The first and second selection signals are output-controlled such that the drive to the odd-numbered block and the drive to the even-numbered block are alternately started. Further, when the first drive signal to drive the printing elements included in the odd-numbered block is generated and outputted to the printhead, and the second drive signal to drive the printing elements included in the even-numbered block is generated and outputted to the printhead, the first and second drive signals are output-controlled such that the output of the second drive signal is started before completion of the output of the first drive signal.
According to still another aspect of the present invention, the foregoing object is attained by providing a printing apparatus that performs printing on a print medium by dividing a plurality of printing elements included in a printhead into a plurality of blocks and time-divisionally driving the respective blocks, comprising: selection-signal generation output means for generating selection signals by using at least two circuits corresponding to at least two structurally-adjacent blocks among the plurality of blocks, to select the at least two blocks, and outputting the selection signals to the printhead; drive-signal generation output means for generating at least two drive signals to drive printing elements included in the respective two structurally-adjacent blocks and outputting the at least two drive signals to the printhead; and control means for output-controlling the selection signals such that drive-start timings of the at least two structurally-adjacent blocks are different from each other, and controlling the selection-signal generation output means and the drive-signal generation output means to control start and end of output of the at least two drive signals such that a period of driving printing elements included in one block of the at least two structurally-adjacent blocks and a period of driving printing elements included in another block overlap with each other.
According to still another aspect of the present invention, the foregoing object is attained by providing a printing control method for performing printing on a print medium by dividing a plurality of printing elements included in a printhead into a plurality of blocks and time-divisionally driving the respective blocks, comprising: a selection-signal generation output step of generating selection signals by using at least two circuits corresponding to at least two structurally-adjacent blocks among the plurality of blocks, to select the at least two blocks, and outputting the selection signals to the printhead; a drive-signal generation output step of generating at least two drive signals to drive printing elements included in the respective two structurally-adjacent blocks and outputting the at least two drive signals to the printhead; and a control step of output-controlling the selection signals such that drive-start timings of the at least two structurally-adjacent blocks are different from each other, and controlling the selection-signal generation output step and the drive-signal generation output step to control start and end of output of the at least two drive signals such that a period of driving printing elements included in one block of the at least two structurally-adjacent blocks and a period of driving printing elements included in another block overlap with each other.
According to still another aspect of the present invention, the foregoing object is attained by providing a printhead that performs printing on a print medium by dividing a plurality of printing elements into a plurality of blocks and time-divisionally driving the respective blocks, comprising: at least two selection-signal generation output circuits that generate and output at least two selection signals in correspondence with at least two structurally-adjacent blocks among the plurality of blocks, to select the at least two structurally-adjacent blocks from the plurality of blocks; and a drive signal receiving unit that receives at least two drive signals to drive printing elements included in the respective at least two structurally-adjacent blocks; wherein the at least two selection signals are output-controlled such that drive start timings of the at least two structurally-adjacent blocks are different from each other, and wherein control is performed by the at least two drive signals such that a period of driving printing elements included in one block of the at least two structurally-adjacent blocks and a period of driving printing elements included in another block overlap with each other.
The invention is particularly advantageous since when drive moves from one block to the next block, printing elements of the respective blocks can be continuously driven.
Thus, the discontinuity in drive to the printing elements, that occurred between blocks in the conventional printing is prevented, and printing can be performed at a higher speed.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.